Worlds of
stormy weather
TRAVEL ADVISORY: Cloudy,
with high-pressure storms
lasting years to centuries
on Jupiter, Saturn, and Nep
tune. On Uranus, no severe
turbulence beyond local
thunderheads.
Such detailed planetary
weather reports are based on
images like this of Jupiter's
Great Red Spot (right) sent back
by Voyager 1 in 1979. Until then
the giant storm, visible by tele
scope for perhaps three centu
ries, seemed little more than
what its name implied: a blotch
amid smooth cloud bands.
Jupiter's atmosphere is enor
mously complex and dwarfs our
own in scale. The Great Red
Spot (whose color varies over
time between red and brown) is
large enough to swallow three
Earths. Like a rock in a stream,
it sends passing clouds spinning
into short-lived eddies. The
white oval passing below-a
50-year-old feature-is a similar
high-pressure cell, although it
lacks the chemical compounds
that we think color the Great
Red Spot. Jupiter, in fact, roils
with tiny versions of the Great
Red Spot. These vortices bring
heat up from the interior, setting
in motion the jet-stream bands.
And the other planets? Our
best theory told us they would
be increasingly less dynamic,
each being farther from the sun
and colder.
Saturn and Uranus fit that
pattern, although Saturn did re
veal winds three times as fast as
NationalGeographic, August 1990